This invention is in the field of multiple photoflash lamp units such as the FlipFlash type of flash array.
U.S. Pat. No. 4,019,043 to Blount discloses a FlipFlash type of array having a metal foil shield positioned behind the circuit board and connected to the electrical ground of the circuit. The metal foil is in the form of a metal coating on a paper indicia sheet which is also provided with flash indicator means to indicate which of the lamps have been flashed. In U.S. Pat. No. 4,133,023 to Hanson, there is also disclosed a FlipFlash type of array having said shield member wherein the electrically insulated flash indicator material extends entirely up the sides of said conducting surface in order to prevent the lamp lead-in wires from becoming shorted against the shield. The still more recently issued U.S. Pat. No. 4,167,773 to Hanson also discloses such type shield member for a FlipFlash type of array wherein said electrically insulated flash indicator material positioned on the front conductive surface extends only partially up the sides of said conductive surface.
The conventional flash lamp arrays thereby utilize separate circuit board and electrical shield members which add both to cost and complexity of producing reliable multiple photoflash units. On the other hand, it is necessary to provide electrical insulation between the electrical circuitry employed to sequentially fire the plurality of flash lamps and a conductive electrical shield serving to reduce the possibility of accidental flashing of said flash lamps by electrostatic voltage charges or a person or object touching the flash lamp array. The present circuit board members provide the needed electrical insulation by having the electrical circuitry deposited on a dielectric substrate which is commonly a synthetic organic polymer material such as polystyrene. Electrical connection of the individual flash lamps in the present FlipFlash array is achieved by connecting both lead-in wires protruding from the individual flash lamps to switching circuitry located on the circuit board and which further includes separate electrical connection to the electrical shield member for grounding of said switching circuitry. It would be desirable, therefore, to achieve sequential firing of the individual flash lamps in a more simple manner and which can be carried out with a minimum modification of the existing multiple photoflash lamp units.